The invention concerns a process for the adaption of the shifting operation in an automatic transmission.
In the case of processes known to the practice, regarding adaption of the shifting operations in an automatic transmission, a determination has been made of adaption values dependent upon shift related occurrences in operation of the automatic transmission. These adaption values were stored in a memory of an electronic control unit to be accessed for the control of gear changes.
Such adaption storage was designated as a characteristic map. Such a map, generally, exhibits two different axes, upon which the adaption values of the said map are apportioned into various classes. Since, in the operation of an automatic transmission, many different application cases happen, the adaption process is framed as intelligent and evaluates external occurrences for the improvement of the quality of shifting. After each happening, that is each shift operation, a determination is made, as to whether the shifting was executed in the optimum manner, or if deviations from a predetermined sequence of shifting operations has occurred.
Governed by monitoring, the adaption map, i.e. the adaption memory, is made to accept that said occurrence at the.respective operating point associated therewith. Or on the other hand, the said memory may experience no change at all.
In general, in the case of automatic transmission shifting operations, engagement and disengagement of the shift elements, namely the clutches, are carried out in accord with pressure curves as predetermined in an electronic control unit. An exact control, that is to say, regulation of the clutches by means of the pressure curves, especially in the case of shifting sequences in the course of the overlap procedure, is integrally responsible for shifting comfort. Processes have been introduced to improve shifting operation, for regulation or control of the said pressure curve variation which are similar to a modified power-shift, or a regulated load take-over. Under these circumstances, the said pressure curves for the clutch operation are broken into a plurality of incremental pressures.
Correction values for these pressure curve variations are input into the predetermined adaption map, dependent upon various parameters, such as, the torque of the input drive and the temperature of the automated transmission, and the speed of rotation of the input drive. These values are incrementalized into classes of torque, and/or temperature and/or rotational speed. The magnitude of the pressure provided through the adaption map takes on the responsibility for undesirable deviations in the shifting action, which, for example, occur because of component tolerances, frictional value changes of the clutch liners, and mechanical wear in the automatic transmission. Also the programming based on the adaption map compensates for the shifting action, which deteriorates with operational time. On this account, for each shift operation executed, that is, a shifting procedure of the automatic transmission by an electronic transmission control, a determination is made by said control, as to whether or not the shifting time was too long, too short, or just right, or whether the specific moment for an awaited speed of rotation was, again, too soon, too late or correct. If, the determination is made in the electronic controller, that an evaluated run of shifting deviates from a specified run of shifting, then the adaption map will be made to conform thereto.
This procedure achieves the goal, that during the increasing of the operational period, very exact adaption maps come into being which react to changing due to wear or aging in the automatic transmission.
However, the disadvantageous aspect of this is, that for the determination of the adaption values, first, a plurality of computer accesses must be made into one of the evaluation storages ahead of the adaption map, until a value of field of an evaluation storage has reached a so-called overflow value, which, finally, can be recorded, i.e. stored in the true adaption map, or be added thereto as a basic value of the adaption map. These steps do not enable a rapid adaption, since first, several of the shifting operations which deviate from the predetermined shifting operation must be carried out, before a final adaption value is available, that is, before a determined adaption value can be employed as a compensation of the deviations.
The continually growing demands on the functionality of the automatic transmission are already at a new level, due to an increased call for gear shifting quality, requirements for more spontaneity, and also because of the increasing number of ratios into which must be shifted. What these demands predominately call for at motor start-up i.e., when the automatic transmission begins to operate, is an immediate action of a quick responding adaption system, to quickly optimize shifting, at least partially, by means of taking advantage of increased tolerance limits. Contrary to this, there is also the requirement, as the running time of the automatic transmission increases, not to provide too radical steps in adaption, since such steps are not likely to be compatible with the adaption, and thus by erroneous interpretation, subsequently erroneous reactions occur with faulty consequences for the adaption.
In order to avoid the disadvantages which accompany the adaption process, as well to properly meet the demands on the functionality of the automatic transmission, the practice has evolved so-called special functions, or forced adaptions, especially triggered by wide discrepancies in the performance of the shifting operation and the large adaption steps which result therefrom. These kinds of special functions react, however, even in an already well ordered situation, by allowing one-time failing reactions of the automatic transmission that is to say, improper interpretations of the adaption process. These reactions, lead in turn, to poorer shifting, until the adaption system back-tracks and corrects these erroneously adapted value by means of the above described xe2x80x9cnormalxe2x80x9d run of the evaluation storage.
Thus, the purpose of the present invention is to make available, a process for the adaption of a shifting operation in an automatic transmission, by means of which, a quickly reacting adaption system is created and in the steady running adaption condition during the operational time of the automatic transmission, erroneous adaptions are avoided to greatest possible extent.
The invented process for the adaption of the shifting operation of an automatic transmission offers the advantage, that the determined adaption values before the storage in the adaption memory, are corrected, based upon a lifetime loading of the automatic transmission and thus can be made to fit the given demands and requirements during the entire lifetime of an automatic transmission. This advantage particularly comes to the fore, in that, in the case of a xe2x80x9cnew automatic transmissionxe2x80x9d, at first, greater adaption steps are carried out and the factually determined adaption values are made to conform, with consideration given to the lifetime loading of the automatic transmission.
Under the term xe2x80x9clifetime loadxe2x80x9d is to be understood, that the running time, or the operational period of the automatic transmission, along with the kilometer accruals and the number of shifts made are incorporated into the adaption, that is to say, into the determination of the adaption values. With this procedure, assurance can be given, that, as operational time increases, a self-sustaining steady running condition of the adaption is brought about and a good, progressive adaption situation is established. This is accomplished without compromising the satisfactory adaption by determined adaption values with step values which are too broad being accepted by the adaption memory only after subjection to a correction, taking into consideration the lifetime load.
Further an advantage is found therein, that with the correction of the adaption value for a known process, an evaluation memory, placed ahead of the adaption value storage, can be dispensed with, so that even upon increasing operational time, a quick adaption of the shifting operation can be executed, without the danger of an undesirable disturbance delaying a smooth running adaption system.